gdb/amd64obsd-tdep.c

   1 /* Target-dependent code for OpenBSD/amd64.
   2
   3    Copyright (C) 2003, 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "frame.h"
  22 #include "frame-unwind.h"
  23 #include "gdbcore.h"
  24 #include "symtab.h"
  25 #include "objfiles.h"
  26 #include "osabi.h"
  27 #include "regcache.h"
  28 #include "regset.h"
  29 #include "target.h"
  30 #include "trad-frame.h"
  31
  32 #include "gdb_assert.h"
  33 #include "gdb_string.h"
  34
  35 #include "amd64-tdep.h"
  36 #include "i387-tdep.h"
  37 #include "solib-svr4.h"
  38 #include "bsd-uthread.h"
  39
  40 /* Support for core dumps.  */
  41
  42 static void
  43 amd64obsd_supply_regset (const struct regset *regset,
  44                          struct regcache *regcache, int regnum,
  45                          const void *regs, size_t len)
  46 {
  47   const struct gdbarch_tdep *tdep = gdbarch_tdep (regset->arch);
  48
  49   gdb_assert (len >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE);
  50
  51   i386_supply_gregset (regset, regcache, regnum, regs, tdep->sizeof_gregset);
  52   amd64_supply_fxsave (regcache, regnum,
  53                        ((const gdb_byte *)regs) + tdep->sizeof_gregset);
  54 }
  55
  56 static const struct regset *
  57 amd64obsd_regset_from_core_section (struct gdbarch *gdbarch,
  58                                     const char *sect_name, size_t sect_size)
  59 {
  60   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  61
  62   /* OpenBSD core dumps don't use seperate register sets for the
  63      general-purpose and floating-point registers.  */
  64
  65   if (strcmp (sect_name, ".reg") == 0
  66       && sect_size >= tdep->sizeof_gregset + I387_SIZEOF_FXSAVE)
  67     {
  68       if (tdep->gregset == NULL)
  69         tdep->gregset = regset_alloc (gdbarch, amd64obsd_supply_regset, NULL);
  70       return tdep->gregset;
  71     }
  72
  73   return NULL;
  74 }
  75 \f
  76
  77 /* Support for signal handlers.  */
  78
  79 /* Default page size.  */
  80 static const int amd64obsd_page_size = 4096;
  81
  82 /* Return whether THIS_FRAME corresponds to an OpenBSD sigtramp
  83    routine.  */
  84
  85 static int
  86 amd64obsd_sigtramp_p (struct frame_info *this_frame)
  87 {
  88   CORE_ADDR pc = get_frame_pc (this_frame);
  89   CORE_ADDR start_pc = (pc & ~(amd64obsd_page_size - 1));
  90   const gdb_byte sigreturn[] =
  91   {
  92     0x48, 0xc7, 0xc0,
  93     0x67, 0x00, 0x00, 0x00,     /* movq $SYS_sigreturn, %rax */
  94     0xcd, 0x80                  /* int $0x80 */
  95   };
  96   size_t buflen = (sizeof sigreturn) + 1;
  97   gdb_byte *buf;
  98   char *name;
  99
 100   /* If the function has a valid symbol name, it isn't a
 101      trampoline.  */
 102   find_pc_partial_function (pc, &name, NULL, NULL);
 103   if (name != NULL)
 104     return 0;
 105
 106   /* If the function lives in a valid section (even without a starting
 107      point) it isn't a trampoline.  */
 108   if (find_pc_section (pc) != NULL)
 109     return 0;
 110
 111   /* If we can't read the instructions at START_PC, return zero.  */
 112   buf = alloca ((sizeof sigreturn) + 1);
 113   if (!safe_frame_unwind_memory (this_frame, start_pc + 6, buf, buflen))
 114     return 0;
 115
 116   /* Check for sigreturn(2).  Depending on how the assembler encoded
 117      the `movq %rsp, %rdi' instruction, the code starts at offset 6 or
 118      7.  */
 119   if (memcmp (buf, sigreturn, sizeof sigreturn)
 120       && memcpy (buf + 1, sigreturn, sizeof sigreturn))
 121     return 0;
 122
 123   return 1;
 124 }
 125
 126 /* Assuming THIS_FRAME is for a BSD sigtramp routine, return the
 127    address of the associated sigcontext structure.  */
 128
 129 static CORE_ADDR
 130 amd64obsd_sigcontext_addr (struct frame_info *this_frame)
 131 {
 132   CORE_ADDR pc = get_frame_pc (this_frame);
 133   ULONGEST offset = (pc & (amd64obsd_page_size - 1));
 134
 135   /* The %rsp register points at `struct sigcontext' upon entry of a
 136      signal trampoline.  The relevant part of the trampoline is
 137
 138         call    *%rax
 139         movq    %rsp, %rdi
 140         pushq   %rdi
 141         movq    $SYS_sigreturn,%rax
 142         int     $0x80
 143
 144      (see /usr/src/sys/arch/amd64/amd64/locore.S).  The `pushq'
 145      instruction clobbers %rsp, but its value is saved in `%rdi'.  */
 146
 147   if (offset > 5)
 148     return get_frame_register_unsigned (this_frame, AMD64_RDI_REGNUM);
 149   else
 150     return get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 151 }
 152 \f
 153 /* OpenBSD 3.5 or later.  */
 154
 155 /* Mapping between the general-purpose registers in `struct reg'
 156    format and GDB's register cache layout.  */
 157
 158 /* From <machine/reg.h>.  */
 159 int amd64obsd_r_reg_offset[] =
 160 {
 161   14 * 8,                       /* %rax */
 162   13 * 8,                       /* %rbx */
 163   3 * 8,                        /* %rcx */
 164   2 * 8,                        /* %rdx */
 165   1 * 8,                        /* %rsi */
 166   0 * 8,                        /* %rdi */
 167   12 * 8,                       /* %rbp */
 168   15 * 8,                       /* %rsp */
 169   4 * 8,                        /* %r8 .. */
 170   5 * 8,
 171   6 * 8,
 172   7 * 8,
 173   8 * 8,
 174   9 * 8,
 175   10 * 8,
 176   11 * 8,                       /* ... %r15 */
 177   16 * 8,                       /* %rip */
 178   17 * 8,                       /* %eflags */
 179   18 * 8,                       /* %cs */
 180   19 * 8,                       /* %ss */
 181   20 * 8,                       /* %ds */
 182   21 * 8,                       /* %es */
 183   22 * 8,                       /* %fs */
 184   23 * 8                        /* %gs */
 185 };
 186
 187 /* From <machine/signal.h>.  */
 188 static int amd64obsd_sc_reg_offset[] =
 189 {
 190   14 * 8,                       /* %rax */
 191   13 * 8,                       /* %rbx */
 192   3 * 8,                        /* %rcx */
 193   2 * 8,                        /* %rdx */
 194   1 * 8,                        /* %rsi */
 195   0 * 8,                        /* %rdi */
 196   12 * 8,                       /* %rbp */
 197   24 * 8,                       /* %rsp */
 198   4 * 8,                        /* %r8 ... */
 199   5 * 8,
 200   6 * 8,
 201   7 * 8,
 202   8 * 8,
 203   9 * 8,
 204   10 * 8,
 205   11 * 8,                       /* ... %r15 */
 206   21 * 8,                       /* %rip */
 207   23 * 8,                       /* %eflags */
 208   22 * 8,                       /* %cs */
 209   25 * 8,                       /* %ss */
 210   18 * 8,                       /* %ds */
 211   17 * 8,                       /* %es */
 212   16 * 8,                       /* %fs */
 213   15 * 8                        /* %gs */
 214 };
 215
 216 /* From /usr/src/lib/libpthread/arch/amd64/uthread_machdep.c.  */
 217 static int amd64obsd_uthread_reg_offset[] =
 218 {
 219   19 * 8,                       /* %rax */
 220   16 * 8,                       /* %rbx */
 221   18 * 8,                       /* %rcx */
 222   17 * 8,                       /* %rdx */
 223   14 * 8,                       /* %rsi */
 224   13 * 8,                       /* %rdi */
 225   15 * 8,                       /* %rbp */
 226   -1,                           /* %rsp */
 227   12 * 8,                       /* %r8 ... */
 228   11 * 8,
 229   10 * 8,
 230   9 * 8,
 231   8 * 8,
 232   7 * 8,
 233   6 * 8,
 234   5 * 8,                        /* ... %r15 */
 235   20 * 8,                       /* %rip */
 236   4 * 8,                        /* %eflags */
 237   21 * 8,                       /* %cs */
 238   -1,                           /* %ss */
 239   3 * 8,                        /* %ds */
 240   2 * 8,                        /* %es */
 241   1 * 8,                        /* %fs */
 242   0 * 8                         /* %gs */
 243 };
 244
 245 /* Offset within the thread structure where we can find the saved
 246    stack pointer (%esp).  */
 247 #define AMD64OBSD_UTHREAD_RSP_OFFSET    400
 248
 249 static void
 250 amd64obsd_supply_uthread (struct regcache *regcache,
 251                           int regnum, CORE_ADDR addr)
 252 {
 253   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 254   CORE_ADDR sp = 0;
 255   gdb_byte buf[8];
 256   int i;
 257
 258   gdb_assert (regnum >= -1);
 259
 260   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 261     {
 262       int offset;
 263
 264       /* Fetch stack pointer from thread structure.  */
 265       sp = read_memory_unsigned_integer (sp_addr, 8);
 266
 267       /* Adjust the stack pointer such that it looks as if we just
 268          returned from _thread_machdep_switch.  */
 269       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 270       store_unsigned_integer (buf, 8, sp + offset);
 271       regcache_raw_supply (regcache, AMD64_RSP_REGNUM, buf);
 272     }
 273
 274   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 275     {
 276       if (amd64obsd_uthread_reg_offset[i] != -1
 277           && (regnum == -1 || regnum == i))
 278         {
 279           /* Fetch stack pointer from thread structure (if we didn't
 280              do so already).  */
 281           if (sp == 0)
 282             sp = read_memory_unsigned_integer (sp_addr, 8);
 283
 284           /* Read the saved register from the stack frame.  */
 285           read_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 286           regcache_raw_supply (regcache, i, buf);
 287         }
 288     }
 289 }
 290
 291 static void
 292 amd64obsd_collect_uthread (const struct regcache *regcache,
 293                            int regnum, CORE_ADDR addr)
 294 {
 295   CORE_ADDR sp_addr = addr + AMD64OBSD_UTHREAD_RSP_OFFSET;
 296   CORE_ADDR sp = 0;
 297   gdb_byte buf[8];
 298   int i;
 299
 300   gdb_assert (regnum >= -1);
 301
 302   if (regnum == -1 || regnum == AMD64_RSP_REGNUM)
 303     {
 304       int offset;
 305
 306       /* Calculate the stack pointer (frame pointer) that will be
 307          stored into the thread structure.  */
 308       offset = amd64obsd_uthread_reg_offset[AMD64_RIP_REGNUM] + 8;
 309       regcache_raw_collect (regcache, AMD64_RSP_REGNUM, buf);
 310       sp = extract_unsigned_integer (buf, 8) - offset;
 311
 312       /* Store the stack pointer.  */
 313       write_memory_unsigned_integer (sp_addr, 8, sp);
 314
 315       /* The stack pointer was (potentially) modified.  Make sure we
 316          build a proper stack frame.  */
 317       regnum = -1;
 318     }
 319
 320   for (i = 0; i < ARRAY_SIZE (amd64obsd_uthread_reg_offset); i++)
 321     {
 322       if (amd64obsd_uthread_reg_offset[i] != -1
 323           && (regnum == -1 || regnum == i))
 324         {
 325           /* Fetch stack pointer from thread structure (if we didn't
 326              calculate it already).  */
 327           if (sp == 0)
 328             sp = read_memory_unsigned_integer (sp_addr, 8);
 329
 330           /* Write the register into the stack frame.  */
 331           regcache_raw_collect (regcache, i, buf);
 332           write_memory (sp + amd64obsd_uthread_reg_offset[i], buf, 8);
 333         }
 334     }
 335 }
 336 /* Kernel debugging support.  */
 337
 338 /* From <machine/frame.h>.  Easy since `struct trapframe' matches
 339    `struct sigcontext'.  */
 340 #define amd64obsd_tf_reg_offset amd64obsd_sc_reg_offset
 341
 342 static struct trad_frame_cache *
 343 amd64obsd_trapframe_cache (struct frame_info *this_frame, void **this_cache)
 344 {
 345   struct trad_frame_cache *cache;
 346   CORE_ADDR func, sp, addr;
 347   ULONGEST cs;
 348   char *name;
 349   int i;
 350
 351   if (*this_cache)
 352     return *this_cache;
 353
 354   cache = trad_frame_cache_zalloc (this_frame);
 355   *this_cache = cache;
 356
 357   func = get_frame_func (this_frame);
 358   sp = get_frame_register_unsigned (this_frame, AMD64_RSP_REGNUM);
 359
 360   find_pc_partial_function (func, &name, NULL, NULL);
 361   if (name && strncmp (name, "Xintr", 5) == 0)
 362     addr = sp + 8;              /* It's an interrupt frame.  */
 363   else
 364     addr = sp;
 365
 366   for (i = 0; i < ARRAY_SIZE (amd64obsd_tf_reg_offset); i++)
 367     if (amd64obsd_tf_reg_offset[i] != -1)
 368       trad_frame_set_reg_addr (cache, i, addr + amd64obsd_tf_reg_offset[i]);
 369
 370   /* Read %cs from trap frame.  */
 371   addr += amd64obsd_tf_reg_offset[AMD64_CS_REGNUM];
 372   cs = read_memory_unsigned_integer (addr, 8);
 373   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 374     {
 375       /* Trap from user space; terminate backtrace.  */
 376       trad_frame_set_id (cache, null_frame_id);
 377     }
 378   else
 379     {
 380       /* Construct the frame ID using the function start.  */
 381       trad_frame_set_id (cache, frame_id_build (sp + 16, func));
 382     }
 383
 384   return cache;
 385 }
 386
 387 static void
 388 amd64obsd_trapframe_this_id (struct frame_info *this_frame,
 389                              void **this_cache, struct frame_id *this_id)
 390 {
 391   struct trad_frame_cache *cache =
 392     amd64obsd_trapframe_cache (this_frame, this_cache);
 393
 394   trad_frame_get_id (cache, this_id);
 395 }
 396
 397 static struct value *
 398 amd64obsd_trapframe_prev_register (struct frame_info *this_frame,
 399                                    void **this_cache, int regnum)
 400 {
 401   struct trad_frame_cache *cache =
 402     amd64obsd_trapframe_cache (this_frame, this_cache);
 403
 404   return trad_frame_get_register (cache, this_frame, regnum);
 405 }
 406
 407 static int
 408 amd64obsd_trapframe_sniffer (const struct frame_unwind *self,
 409                              struct frame_info *this_frame,
 410                              void **this_prologue_cache)
 411 {
 412   ULONGEST cs;
 413   char *name;
 414
 415   /* Check Current Privilege Level and bail out if we're not executing
 416      in kernel space.  */
 417   cs = get_frame_register_unsigned (this_frame, AMD64_CS_REGNUM);
 418   if ((cs & I386_SEL_RPL) == I386_SEL_UPL)
 419     return 0;
 420
 421   find_pc_partial_function (get_frame_pc (this_frame), &name, NULL, NULL);
 422   return (name && ((strcmp (name, "calltrap") == 0)
 423                    || (strcmp (name, "osyscall1") == 0)
 424                    || (strcmp (name, "Xsyscall") == 0)
 425                    || (strncmp (name, "Xintr", 5) == 0)));
 426 }
 427
 428 static const struct frame_unwind amd64obsd_trapframe_unwind = {
 429   /* FIXME: kettenis/20051219: This really is more like an interrupt
 430      frame, but SIGTRAMP_FRAME would print <signal handler called>,
 431      which really is not what we want here.  */
 432   NORMAL_FRAME,
 433   amd64obsd_trapframe_this_id,
 434   amd64obsd_trapframe_prev_register,
 435   NULL,
 436   amd64obsd_trapframe_sniffer
 437 };
 438 \f
 439
 440 static void
 441 amd64obsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 442 {
 443   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 444
 445   amd64_init_abi (info, gdbarch);
 446
 447   /* Initialize general-purpose register set details.  */
 448   tdep->gregset_reg_offset = amd64obsd_r_reg_offset;
 449   tdep->gregset_num_regs = ARRAY_SIZE (amd64obsd_r_reg_offset);
 450   tdep->sizeof_gregset = 24 * 8;
 451
 452   set_gdbarch_regset_from_core_section (gdbarch,
 453                                         amd64obsd_regset_from_core_section);
 454
 455   tdep->jb_pc_offset = 7 * 8;
 456
 457   tdep->sigtramp_p = amd64obsd_sigtramp_p;
 458   tdep->sigcontext_addr = amd64obsd_sigcontext_addr;
 459   tdep->sc_reg_offset = amd64obsd_sc_reg_offset;
 460   tdep->sc_num_regs = ARRAY_SIZE (amd64obsd_sc_reg_offset);
 461
 462   /* OpenBSD provides a user-level threads implementation.  */
 463   bsd_uthread_set_supply_uthread (gdbarch, amd64obsd_supply_uthread);
 464   bsd_uthread_set_collect_uthread (gdbarch, amd64obsd_collect_uthread);
 465
 466   /* OpenBSD uses SVR4-style shared libraries.  */
 467   set_solib_svr4_fetch_link_map_offsets
 468     (gdbarch, svr4_lp64_fetch_link_map_offsets);
 469
 470   /* Unwind kernel trap frames correctly.  */
 471   frame_unwind_prepend_unwinder (gdbarch, &amd64obsd_trapframe_unwind);
 472 }
 473 \f
 474
 475 /* Provide a prototype to silence -Wmissing-prototypes.  */
 476 void _initialize_amd64obsd_tdep (void);
 477
 478 void
 479 _initialize_amd64obsd_tdep (void)
 480 {
 481   /* The OpenBSD/amd64 native dependent code makes this assumption.  */
 482   gdb_assert (ARRAY_SIZE (amd64obsd_r_reg_offset) == AMD64_NUM_GREGS);
 483
 484   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 485                           GDB_OSABI_OPENBSD_ELF, amd64obsd_init_abi);
 486
 487   /* OpenBSD uses traditional (a.out) NetBSD-style core dumps.  */
 488   gdbarch_register_osabi (bfd_arch_i386, bfd_mach_x86_64,
 489                           GDB_OSABI_NETBSD_AOUT, amd64obsd_init_abi);
 490 }